Exam Learning Objectives and Kahoot Flashcards
What is ganglion?
Collection of neuronal cell bodies located outside of the central nervous system
Where are ganglia located?
Outside of the CNS
What are the 3 layers of connective tissue surrounding a nerve?
Epineurium:
- Contain the major blood vessels
Perineurium:
- Contains bundles of axons known as fascicles.
Endoneurium:
- Connective tissue surrounding axons
Name all the cranial nerves:
- Olfactory (I)
- Optic (II)
- Oculomotor (III)
- Trochlear (IV)
- Trigeminal (V)
- Abducens (VI)
- Facial (VII)
- Vestibulocochlear (VIII)
- Glossopharyngeal (IX)
- Vagus (X)
- Accessory (XI)
- Hypoglossal (XII)
Describe the function of each cranial nerve:
- Olfactory (I) = smell
- Optic (II) = vision
- Oculomotor (III) = eye movement and pupil constriction
- Trochlear (IV) = 1 eye muscle (superior oblique)
- Trigeminal (V) = sensation to face and meninges, muscles of mastification
- Abducens (VI) = 1 eye muscle (lateral rectus)
- Facial (VII) = facial expression, taste to anterior 2/3, sensation to small portion of skin in the ear.
- Vestibulocochlear (VIII) = cochlear apparatus of inner ear (hearing, vestibular apparatus of the inner ear (balance)
- Glossopharyngeal (IX) = Taste remainder of tongue, sensation to the pharynx, middle ear and some of outer ear.
- Vagus (X) = taste remainder of oral cavity
- Accessory (XI) = some pharyngeal muscles, upper traps and SCM muscles.
- Hypoglossal (XII) = muscles of tongue
General role of the subtypes of motor and sesnory nerves in CN:
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Sensory types can be:
Somatic sensory – sensation from the body like the spinal nerves
Special sensory – senses like vision, hearing, balance and taste
Visceral sensory – sensation from the internal organs
Motor types can be:
Somatic motor - to regular skeletal muscle
Branchial arch motor – skeletal muscle that arises from the branchial arches
Visceromotor – parasympathetic supply to much of the body
What are structures that the autonomic motor efferents act on?
Smooth and cardiac muscle:
- Gut muscles
- Arterial muscle
- Pupil muscles
- Heart muscle
Mostly involuntary
What differences are there between the motor efferent of the somatic and autonomic nervous system:
Somatic:
- Single Neuron Pathway:
An alpha motor neurone in the ventral horn projects directly to the muscle
- Neurotransmitter:
Acetylcholine
- Target:
Skeletal muscle fibers
- Effect:
Muscle contraction (excitation only)
- Control: Voluntary (conscious)
- Functions: Body movement, posture, respiration, speech.
Autonomic:
- Neurotransmitters:
Preganglionic: Acetylcholine
Postganglionic:
* Sympathetic: Norepinephrine (mainly), Acetylcholine (in sweat glands and some blood vessels)
* Parasympathetic: Acetylcholine
- Targets:
Smooth muscle, cardiac muscle, glands
- Effects:
Excitation or inhibition, depending on the receptor type and organ.
- Control:
Involuntary (unconscious)
- Functions:
Regulates heart rate, blood pressure, digestion, respiration, body temperature, and other visceral functions.
Which neurotransmitters are used in the SNS and PNS (which are pre- and post-ganglionic fibers)?
SNS:
- Pre = acetylcholine
- Post = adrenaline
PNS:
- Pre = acetylcholine
- Post = acetylcholine
What are the two main plexus of the ENS and what are their functions?
Myenteric Plexus (Auerbach’s Plexus):
- Located between the longitudinal and circular muscle layers, primarily controlling motility.
Submucosal Plexus (Meissner’s Plexus):
- Located in the submucosa, regulating blood flow, secretions, and absorption.
What are the actions of the PNS?
Rest and repair” system (or “rest and digest”):
- Decrease heart rate
- Dilate the visceral blood vessels to increase
blood perfusion to allow absorption of
nutrients
- Inhibit SNS to dilate peripheral blood vessels
(note peripheral blood vessels only have SNS
innervation) – reduces blood pressure
- Constrict the pupils
- Increase digestion and repair functions
- Increase bladder contraction
- Increase immune system function
- Facilitates neuroplasticity (synaptic
connections)
What are the actions of SNS?
Fight, flight or reproduce system:
- Increase heart rate
- Constrict the blood vessels to increase blood
pressure and improve (short-term) tissue
perfusion
- Dilate the pupils to allow more light to the
retina
- Relax airway muscles to increase O2 intake
- Slow digestion and repair functions
- Release sugar into the blood stream to allow
for energy production
- Cause sweating and piloerection
- Reduces bladder contraction
- Depresses immune system function
What sections of the spine do the SNS and PNS arise from?
SNS:
- T1 to L2/3
PNS:
- S2-4
What occurs in a crossed cord reflex?
When a muscle on one side of the body is activated, like the right biceps, the body automatically adjusts other muscles for balance by:
Inhibiting the antagonist:
- The opposite muscle on the same side (right triceps) is relaxed to allow the biceps to work smoothly.
Facilitating the contralateral antagonist:
- The opposing muscle on the opposite side (left triceps) is activated to help with balance.
Inhibiting the contralateral agonist:
- The same muscle on the opposite side (left biceps) is relaxed to avoid unnecessary movement.
This coordination helps maintain balance and stability during movement.
What would happen in the right tricep and bicep with activation of the left bicep?
Will relax
What is an example of a polysnaptic reflex?
An example of a polysynaptic reflex is the withdrawal reflex, which occurs when the body moves away from a painful stimulus.
- Crossed cord reflexes
What is the differences between short and long latency reflexes? Which pathways and systems are utilized for each type?
Short:
- Rapid response to postural pertubations (20-45ms)
- Spinal cord pathways, including monosynaptic muscle stretch and polysnapatic crossed cord.
- E.g. leaning forward will stretch the gastrocnemius, causing contraction of the gastroc. to counteract the lean
However, these may:
- Be insufficient
- Too strong
- Be incorrect for the given situation
Leading to further imbalance
Long:
- More integrated responses to postural perturbations (50-100 ms)
- Take into account more aspects of posture and goal of behaviour
- Brainstem pathways, including inputs from the vestibular system, visual system and proprioceptive system
- Result in descending responses back to the spinal cord to modulate spinal cord reflexes and alpha motor neurones directly
Free nerve endings may respond to what type of stimuli?
Membrane may contain receptor proteins that respond/open to:
- Pressure
- Chemicals
- Temperature
Free nerve endings often associated with pain sensation
What are free nerve endings commonly associated with?
Pain sensation (nociception)
What is the difference between exteroceptors and interceptors? Give examples
Exteroceptors transduce information from the external environment:
- Light for vision
- Pressure for touch etc
Interoceptors transduce information from the internal environment:
- Stretch receptors from the gut
- Blood pressure receptors in the aorta
What are the primary actions of each of the eye muscles?
- The medial and lateral recti move the eye
medial or laterally respectively - The action of the obliques depends on the
position of the eye - The “neutral” position of the eye is looking
straight ahead
Lateral Rectus = Abduction
Medial Rectus = Adduction
Superior Rectus = Elevation
Inferior Rectus = Depression
Superior Oblique = Intorsion
Inferior Oblique = Extorsion
What are the differences between rods and cones? Where are each one more densely located, and what do they do?
Rods:
- More sensitive to light therefore better in low
light situations
- Better at detecting movement and contrast
- Do not detect colour
- Fewer rods on the macula, more in the
peripheral retina.
Cones:
- Detect colour
- Higher acuity than rods (better for fine detail)
- More cones in the macula, fewer in the
peripheral retina.
Monosynaptic reflex
- Muscle Stretch Reflexes
- Very fast
Components:
- Muscle spindles in the muscle being tested –
these detect stretch in a muscle
- Ia afferent neurone that connects the spindle
to the spinal cord – very fast conduction –
synapses onto the motor neurone
- Alpha motor neurone synapses onto the
muscle causing excitation
Postural reflexes
- Allow us to maintain an upright posture
- To maintain an upright posture you must first
be able to detect when you are deviating
from a sufficiently upright position:- Receptors are needed to do this
- Your system must then determine an
appropriate response:- The CNS must process
- Your system must then execute that
response effectively- Effective motor systems are needed
Cutaneous receptors
- The neurone may connect to specialised
receptors in the skin - These cells respond to different types of
stimuli
Examples include:
- Merkel’s Disc
- Pacinian Corpuscles
- Meissner Corpuscles
- Ruffini Endings
What are the names of the ossicles of the inner ear?
Malleus, incus, and stapes
What are the names of the muscles of the middle ear? What is their purpose/function?
Tensor tympani (a) and stapedius (b) muscles dampen ossicle movement:
- This will reduce the amplitude (intensity) of
the vibration transmitted
What movements are detected by each of the semicircular canals?
Anterior – detects forward rotations of the head
Posterior – detects backward movements of the head
Horizontal – detects side to side rotations
